Method of making lead alloys



May 2, 1939. H. s. COOPER METHOD QF MAKING LEAD ALLOYS Filed March '7,1934 a N? M aw m 0Q Patented May 2, 1939 UNITED STATES PATENT OFFICMETHOD OF MAKING LEAD ALLOYS Hugh S. Cooper, Shaker Heights, Ohio,assignor to Cooper Products, Inc., Cleveland, Ohio, a corporation ofOhio The present invention relates to metal alloys or conglomeratescomprising lead and a method of making the same. More particularly theinvention relates to alloys or conglomerates of lead and certain metals,compounds, especially the oxides, of which are reducible preferably byhydrogen at temperatures below or not greatly in excess of thevaporization temperature of lead, such as copper, silver, iron, nickel,cobalt, tungsten, and molybdenum.

If an attempt is made to prepare alloys or conglomerates of lead and oneor more metals, such as those noted above, by the common method ofmelting and casting, the lead rapidly separates itself from the other orothers during the cooling process, owing to the immiscibility of themetals in the liquid state. In the resulting product the lead is eitherunevenly distributed or may possibly be segregated completely from theother metal or metals. Various attempts have been made to prevent theseparation of the lead from the other metals, such as the addition ofsulphur, tin, etc., without success. According to the present invention,alloys or conglomerates comprising lead are produced which have auniform or other predetermined distribution of the lead throughout theproduct as the metals combined never reach a melted or molten state, andconsequently there can be no separation of the lead. The alloys and/orconglomerates of the present invention have special utility as bearingmetals.

An object of the present invention is the provision of a novel alloy orconglomerate compris- 35 ing lead in which there will be a predetermineddistribution of the lead throughout the same.

Another object of the invention is the provision of a novel alloy and/orconglomerate comprising lead and a metal the oxide of which is 0reducible by hydrogen at temperatures less than or not greatly in excessof the vaporization temperature of lead.

Another object of the invention is the provision of a novel alloy and/orconglomerate com- 45 prising lead and copper, silver, iron, nickel, co-

balt, tungsten, and/or molybdenum in which the lead will be uniformlydistributed through the product.

Another object of the invention is the provision of a novel bearingmetal containing lead in which the lead has a predetermined or a uniformdistribution throughout the product.

Another object of the invention is the provision of a novel bearing,bushing, etc. containing 55 lead in which the distribution of the leadthroughout the article is either uniform or predetermined.

Another object of the invention is the provision of a novel method ofmaking an alloy and /or conglomerate of lead which comprises preparing apredetermined mixture of compounds of the metals to be alloyed, reducingthe compounds, subsequently compressing the resulting product, andsintering at a temperature less than or not greatly exceeding thevaporization temperature of the metals. I

Another object of the invention is the provision of a novel method ofmaking an alloy and/or conglomerate containing lead which comprisespreparing a uniform mixture of the oxides of the metals tobe combined,reducing the mixture by hydrogen at a'temperature less than thevaporization temperature of lead which will produce a fine powder,subsequently compressing the resulting powder, and sintering at atemperature at which the lead will not sweat out of the mass.

Further objects and advantages of the present invention will be apparentto those skilled in the art to which it pertains from the followingdescription of the preferred embodiments of the alloys and /orconglomerates and preferred methods of making the same, described withreference to the accompanying drawing, in which:

Fig. 1 is a perspective view, with a portion in section, of a valveguide embodying the present invention;

Fig. 2 is a perspective view, with a portion in se tion, of a bushingembodying the present invention;

Fig. 3 is a perspective view of a rolled sheet of material embodying thepresent invention; and

Fig. 4 is a perspective view of a bearing cap lined with bearing metalof the present invention.

According to the present invention, alloys con-' taining lead, having auniform distribution of the lead through the finished product, areproduced by a method which contemplates the reduction, preferably byhydrogen, of a mixture of powdered compounds, preferably oxides, of the,metals to be combined at a temperature less than the vaporizationtemperature of lead which will produce a uniform, fine powder, afterwhich the resulting powder or mass is pressed to any desired form andsintered at a temperature less than the vaporization temperature of leadat which the lead will not sweat out of the mass. The sintered productmay be finished as desired in any suitable manner, such as by machining,

etc., or it may be rolled into sheets, etc. During the process themetals never reach a molten state, and, consequently, there can be noseparation of the lead and a uniform distribution of the lead throughoutthe product is obtained.

For the purpose of more clearly illustrating the invention, lead-copper,lead-tungsten, and lead-iron alloys or conglomerates will bespecifically described, together with the method of making the same, asthe preferred embodiments of the invention, but it will be understoodthat the invention is not limited to these specific alloys.

In the preparation of a metal compound containing approximately 50% eachof lead and copper, a mixture of powdered lead oxide and powdered copperoxide in the proportion of 223 parts of the lead-compound to 237 partsof the copper compound by weight, as a specific example say 223 grams oflead oxide (PhD) and 237 grams of copper oxide (CuO), is thoroughlymixed for several hours in a porcelain mill to obtain a uniformcomposition. The loose powder is then placed in boats, which may beeither iron or nickel, etc., and heated in hydrogen at approximately 500C. for about two hours, or until the oxides are completely reduced and auniform fine powder is produced. The powder has an appearance ofinterwoven crystals, isof a bronze color, and is very fine and uniformin composition. The resulting powder is pressed to the desired shapebetween steel dies at pressures ranging from about 10,000 to 25,000pounds per square inch, and subsequently sintered in hydrogen attemperatures around 500 C. The alloy or conglomerate thus obtained makesa very suitable bearing metal and contains a uniform distribution of thelead throughout the copper. When it is desired to make bearings orbushings such as illustrated in Fig. 2 of the drawing, the reducedpowder is preferably pressed to an appropriate shape before thesintering step, and after sintering, is machined to size, etc. If it isdesired to roll the material into sheets, the reduced powder is merelypressed into a rectangular slug and sintered, after which the slug maybe rolled to any desired shape and thickness. If desired, other metalsmay be added, such as iron in the form of iron oxide, and it is to beunderstood that the proportions of the various metals may be varied asdesired within Wide limits so long as lead is present in substantialamounts.

A lead-tungsten alloy or conglomerate containing approximately 50% eachof lead and tungsten maybe prepared in a similar manner. A mixture ofpowdered lead oxide and powdered tungsten oxide in the proportion of 223parts of the lead compound to 232 parts of the tungsten compound, byweight, for example 223 grams of lead oxide (PhD) and 232 grams oftungsten oxide (W03) when thoroughly mixed, as outlined above, andreduced by hydrogen at temperatures ranging from 700 C. to 950 0.,yields a very uniform, fine gray powder which, when compressed and.sintered at approximately 700 C. gives an alloy of high ductilityshowing a hardness of from 30 to 40 on the Brinell scale, and one whichhas a uniform distribution of lead throughout the resultant product.Sections of this alloy which are not too thick are so malleable thatthey can be rolled to thin sheets as was the case with the lead-copperalloy referred to above. The proportions of lead and tungsten may bevaried as desired, and other metals may be added thereto, such asmolybdenum. Compounds other than arcades the oxides of the metals mayalso be used, such as ammonium tungstate in place of the tungstenoxides.

Lead-iron alloys or conglomerates oi approximately 50% each of lead andiron having a uniform distribution of the lead throughout the productmay be produced by thoroughly mixing powdered lead oxide with powderediron oxide in the proportions of approximately 223 parts of the leadcompound to 300 parts of the iron compound by weight. As a specificexample, 223 grams of powdered lead oxide (PbO) are thoroughly mixedwith 300 grams of iron oxide (F8203) until a uniform powder is produced.This powder, when reduced by heating in hydrogen at approximately 700 C.for about one hour, produces a very uniform, fine, dark gray or blackpowder which is compressed and sintered at approximately 500 C. Thesintered product is quite malleable and shows a Brinell hardness ofabout 60 to 70. This product differs from the other alloys noted abovein that it can be heated to 600 C. without evidence of lead-sweating andwith but very little change in hardness. The proportions of lead oxideand iron oxide may be varied as desired, thereby obtaining alloys of anydesired composition, and other metals, such as nickel, may be addedthereto in a similar manner.

Due, to the high lubricating value of lead, the

compounds of the present invention, especially those containing asubstantial proportion of lead,

are especially suited for making bearings, bushings, valve guides, etc.Whether or not the metal compounds of the present invention are truealloys or conglomerates of a combination of each is indetermined andprobably depends upon the particular combination of metals employed inany specific product, and is considered immaterial for the purposes ofthe present invention.

Referring to the drawing, Fig. 1 illustrates a valve guide designated ingeneral by the reference character l0 and embodying the presentinvention. The particular valve guide illustrated comprises a tubularbody portion provided with a flange I I at the upper end thereof and ismade of the lead-tungsten metal composition previously described bypressing the fine powder resulting from the reducing step of the processinto approximately the desired shape, and, after sintering, machining tosize.

Fig. 2 of the drawing illustrates a bushing l2 made of the lead-coppercomposition described by pressing the lead oxide copper oxide powder,after being reduced, into the shape illustrated and sintering.

Fig. 3 illustrates a sheet l3 of the lead-iron composition which hasbeen rolled to the shape shown from a cubical sintered slug.

A bearing cap M comprising a conventional steel or iron back i5 linedwith a lead-copper composition l6 made in accordance with the presentinvention is shown in Fig. 4. The particular lining illustrated is 50%each of lead and copper with a uniform distribution of the leadthroughout the copper and has been cut from a rolled sheet of thematerial.

From the foregoing disclosure of the invention it will be apparent thatnew metal compounds, bearing metals, bearings, and bushings have beenproduced, i. e., compounds, bearing metals, bearings, and bushingscomprising lead having a uniform or other predetermined distribution ofthe lead throughout the product. It will also be apparent from theforegoing that new and improved methods of producing metal compoundsawopoa and articles containing lead have been produced.

It is not intended to be limited to the specific metals, compounds,articles, and methods mentioned, as it will be apparent from theforegoing that metals other than those mentioned may be employed, thatcompounds of the metals other than the oxides may be used, that theinitial metal powder may be reduced by agents other than hydrogen, thatvarious proportions and distributions of the metals may be used andobtained, and that the products of the invention have innumerable uses.When the products are to be used for hearing purposes, the lead ispreferably present in quantities ranging from to 80% of the whole.

While I have described the preferred embodiments of my invention, it ismy intention to cover any and all variations, adaptations or usesthereof as come within the knowledge and customary practice in the artto which it appertains, and I specifically point out and claim as myinvention the following:

i. The method or mahng a sintered metallic composition consisting oflead and other metal in which the lead is tmiformly distributed whichcomprises reducing by hydrogen at a temperature less thanthe'va'porization point of lead a uniform mixture consisting of leadoxide and the oxide of a metal reducible by hydrogen at a per, whichcomprises reducing a uniform mixture ofapproximately to lead oxide andthe balance substantially copper oxide by a gaseous substance atapproximately 500 6., compressing the reduced composition to a desiredshape, and subsequently sintering the compressed composition atapproximately 500 C.

HUGH B. COOPER.

